Remixed from Funi's design. This version is designed to attach a 1" Schedule-40 PVC pipe vertical, and then attach the vacuum hose at the other end of the PVC near the top of the router.
The "with supports" file also includes supports inside the tube, which may be slightly difficult to remove.
7/30/2014: Printed successfully using a 3mm brim setting. Got most of the internal support removed with a screwdriver and a small file.
Turn on "brim." I used 3mm.
edit 3/3/2016: Part is modeled in inches. If it looks tiny, scale by 2540%.
edit 4/15/2017: Added .prt files. Can only be opened with student version of Creo.